This invention relates to a recording disk device, such as a floppy disk device, having a flexible recording disk medium, such as a magnetic disk medium, contained in a cartridge or a jacket.
A conventional recording disk device comprises a magnetic disk medium and a jacket body comprising upper and lower shells forming a space to receive the magnetic disk medium. The upper and the lower shells are provided with upper and lower head windows, respectively, to permit an access to the magnetic disk medium by a pair of magnetic heads. The magnetic disk medium is made of a magnetic material having a flexibility. Upper and lower liners are attached to inner surfaces of the upper and the lower shells, respectively. Each of the liners serves to remove fine dust attracted onto the surface of the magnetic disk medium. Therefore, each liner is preferably arranged as close as possible to the surface of the magnetic disk medium.
For this purpose, a lifter in the form of a leaf spring is attached at its one end to the inner surface of the lower shell. The other end of the lifter pushes the lower liner and the magnetic disk medium upward to press the magnetic disk medium against the upper liner attached to the upper shell. Thus, the lifter serves to enhance partial mutual contact between the magnetic disk medium and each of the upper and the lower liners so that the fine dust adhered to the magnetic disk medium is more effectively removed by the upper and the lower liners during rotation of the magnetic disk medium.
Since the magnetic disk medium comprises a flexible thin sheet typically made of synthetic resin with a magnetic recording layer and a coating layer formed thereon, the magnetic disk medium is partially deformed and bent by receiving the pushing force of the lifter through the lower liner. Accordingly, when the magnetic disk medium rotates, a part of the medium is deformed at a position of the lifter and is then restored by elastic force of the magnetic disk medium itself after passing through the lifter position. Therefore, during the rotation of the magnetic disk medium, a recording surface of the magnetic disk medium is fluttered in the vertical direction.
The above-mentioned fluttering will change the condition of sliding contact between the recording surface of the magnetic disk medium and the magnetic head. This results in unstable reading/writing operations by the magnetic head.
Such tendency is noticeable particularly when the magnetic disk medium has a high recording density, and is more or less responsible for the occurrence of errors in the reading/writing operations by the magnetic head.
Since the magnetic disk medium is partially pushed up by the lifter, a load torque is inevitably increased during the rotation of the magnetic disk medium driven by a motor.
In other words, since the liner is very close to the magnetic disk medium, a torque loss is caused to reduce the torque for rotating the magnetic disk medium by the motor. With an increase in torque loss, data writing/reading operations upon the magnetic disk medium become unstable and unreliable.
Furthermore, the lifter is formed by shaping an elastic plate material and must be securely fixed to the lower shell. This results in a decrease in efficiency in manufacture and assembling.